Home   Chapter Home   Jobs   Conferences   Fellowships   Books



Coagulation laboratory tests

Factor XIII assay

Reviewer: Jeremy Parsons, M.D. (see Reviewers page)
Revised: 21 June 2012, last major update June 2012
Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.


● Patients with familial bleeding disorder but normal PT and PTT and normal von Willebrand panel
● Factor XIII deficiency causes delayed bleeding after clot formation due to deficient crosslinking of the fibrin clot

Screening assay:
● Evaluates clot stability in 5M urea
● Add calcium to patient plasma to make it clot, incubate for 30 minutes at 37C, then place clot in 5M urea for 24 hours at room temperature
● Normal patients have stable cots, but patients with factor XIII deficiency of 1-2% of normal have clots that dissolve in urea
● Screening assay does not detect heterozygotes
● 2% acetic acid can also be used as a clot stability screening reagent, but will only detect patients down to 4% deficiency

Quantitative assay:
● Reference range is 70-140% of normal
● Detects values of 50% of normal (heterozygous deficiencies)
● Expensive and not readily available, factor XIII is activated by thrombin, attaches glycine ethyl ester to a peptide substrate, releasing ammonia detected by photometer
● High serum ammonia levels falsely decrease the result
● Newborns may have lower levels than adults

Additional references

Parsons, J.C. Factor XIII Deficiency. LabQ 2012 (ASCP);CL-11:79

End of Coagulation > Coagulation laboratory tests > Factor XIII assay

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.com with any questions (click here for other contact information).